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DS90UB913A-Q1 GPO2 No CLK Output with working External Oscillator

Luis Cordova
Intellectual 1940 points

Hi,

I am trying to connect my board, which has the DS90UB913A and an imager+ISP combo, to the Deserializer EVM. It is set up for External Oscillator Mode. At the moment, when I connect my board to the EVM through a Coax cable, there is no LOCK condition and there is no output clock from GPO2 to the imager, but the external oscillator is working at the expected frequency. The deserializer is set for 12-bit High Frequency Mode, and the external oscillator frequency to the serializer is 27MHz.

I tried changing the deseriailzer to 12-bit low frequency mode with no change in behavior; still no output clock from pin GPO2 and no lock.

I have compared the results with my board to a previous and known working board. Besides the imager used, the main difference in this previous and known serializer design is that the external oscillator frequency is 48MHz. The deserializer board in these tests was set for 12-bit high frequency mode.

Could the issue be in the power sequence of the board? Or the MODE pin?

Any help is sincerely appreciated.

TIDA-01002 Preliminary Schematic.pdf

  • 0
    TI__Intellectual 1940 points

    Original issue I found was the PDB was not pulled up to VDDIO. When I made the change to pull up to VDDIO, I was having the same issue, leading me down this route.

    I connected the correct side of the pull-up resistor to VDDIO = 2.8V (as opposed to VDD = 1.8V, which was below the required 1.96V for a valid logic level high), PDB comes out of reset, and I get a LOCK now.